A post-processing apparatus that performs post-processing on sheets transported from an image-forming apparatus is known. The post-processing apparatus includes a processing tray and a standby tray. In the processing tray, post-processing is performed. The standby tray is provided above the processing tray. During the post-processing performed on sheets in the processing tray, the standby tray temporarily retains subsequent sheets. When the processing tray becomes empty, the standby tray drops the retained sheets toward the processing tray. Further, the post-processing apparatus includes a pressing mechanism that presses the sheets toward the processing tray when the sheets are moved from the standby tray to the processing tray. The pressing mechanism presses the sheets toward the processing tray and thus can quickly move the sheets from the standby tray to the processing tray. Incidentally, the sheets transported by the standby tray may have curls. In the case where the sheets have curls, depending on the configuration of the pressing mechanism, the sheets may be pushed out in an unintentional direction. If the sheets are pushed out in an unintentional direction, the movement of the sheets may be made unstable.